US11746883B2 - Power transmission device - Google Patents

Abstract

A power transmission device includes a box, a case disposed in the box, a differential mechanism housed in the case, and a planetary gear mechanism disposed in the box and supported by the case. The planetary gear mechanism includes a sun gear and a pinion gear that engages with the sun gear. The box has a shelf part above a horizontal line that passes through a revolution center of the pinion gear. The shelf part is arranged at a position that does not overlap the sun gear when viewed from radially above.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a U.S. national phase application of PCT/JP2020/045423, filed on Dec. 7, 2020, which claims priority to Japanese Patent Application No. 2019-240044, filed on Dec. 30, 2019. The entire disclosure of Japanese Patent Application No. 2019-240044 is hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a power transmission device.

BACKGROUND ART

Disclosed in Japanese Laid-Open Patent Application Publication No. H08-240254 is a power transmission device for an electric automobile that has a bevel gear type differential mechanism and a planetary gear mechanism. The planetary gear mechanism ofPatent Document 1 comprises a stepped pinion gear having a large pinion gear and a small pinion gear.

SUMMARY

In the power transmission device, the constituent components of the power transmission device are arranged closely. To suitably lubricate each of the closely arranged constituent components, various contrivances are necessary, and there is a desire to have a structure with a high degree of freedom in lubrication design in power transmission devices.

A power transmission device according to one embodiment comprises: a differential mechanism, a case that houses the differential mechanism, and a pinion gear supported by the case, inside a box, wherein the box has a shelf part above the horizontal line that passes through the revolution center of the pinion gear.

According to certain modes of the present invention, it is possible to provide a power transmission device having a structure with a high degree of freedom for lubrication design.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG.1 is a skeleton diagram of a power transmission device.

FIG.2 is a cross section schematic diagram of the power transmission device.

FIG.3 is an enlarged view around a planetary reduction gear of the power transmission device.

FIG.4 is an enlarged around a differential mechanism of the power transmission device.

FIG.5 is a perspective view of the differential mechanism of the power transmission device.

FIG.6 is an exploded perspective view of the differential mechanism of the power transmission device.

FIG.7 is a drawing for explaining a first case unit of the differential mechanism.

FIG.8 is a drawing for explaining the first case unit of the differential mechanism.

FIG.9 is a drawing for explaining the first case unit of the differential mechanism.

FIG.10 is a drawing for explaining the first case unit of the differential mechanism.

FIG.11 is a drawing for explaining a second case unit of the differential mechanism.

FIG.12 is a drawing for explaining the second case unit of the differential mechanism.

FIG.13 is a drawing for explaining the second case unit of the differential mechanism.

FIG.14 is a drawing for explaining the second case unit of the differential mechanism.

FIG.15 is a drawing for explaining the second case unit of the differential mechanism.

FIG.16 is a drawing for explaining the second case unit of the differential mechanism.

FIG.17 is a drawing for explaining an oil catch unit.

FIG.18 is a drawing for explaining the oil catch unit.

FIG.19 is a drawing for explaining the oil catch unit.

FIG.20 is a drawing for explaining the oil catch unit.

FIG.21 is a drawing for explaining the oil catch unit.

FIG.22 is a drawing for explaining the oil catch unit.

FIG.23 is a drawing for explaining the oil catch unit.

FIG.24 is a drawing for explaining the oil catch unit.

FIG.25 is a drawing for explaining the oil catch unit.

DETAILED DESCRIPTION OF EMBODIMENTS

Following, an embodiment of the present invention is explained.

FIG.1 is a skeleton diagram for explaining apower transmission device1 according to the present embodiment.

FIG.2 is a cross section schematic diagram for explaining thepower transmission device1 of the present embodiment.

FIG.3 is an enlarged view around a planetary reduction gear4 of thepower transmission device1.

FIG.4 is an enlarged view around adifferential mechanism5 of thepower transmission device1.

As shown inFIG.1, thepower transmission device1 has amotor2, and the planetary reduction gear4 (reduction mechanism) that reduces the output rotation of themotor2 and inputs it to thedifferential mechanism5. Thepower transmission device1 also has drive shafts9 (9A,9B) as the drive shaft, and apark lock mechanism3.

In thepower transmission device1, thepark lock mechanism3, the planetary reduction gear4, thedifferential mechanism5, and the drive shafts9 (9A,9B) are provided along the transmission route of the output rotation around the rotation axis X of themotor2. The axis line of the drive shafts9 (9A,9B) is coaxial with the rotation axis X of themotor2.

In thepower transmission device1, after being reduced by the planetary reduction gear4 and inputted to thedifferential mechanism5, the output rotation of themotor2 is transmitted via the drive shafts9 (9A,9B) to left and right drive wheels W, W of a vehicle in which thepower transmission device1 is mounted.

Here, the planetary reduction gear4 is connected downstream of themotor2, thedifferential mechanism5 is connected downstream of the planetary reduction gear4, and the drive shafts9 (9A,9B) are connected downstream of thedifferential mechanism5.

As shown inFIG.2, abody box10 of thepower transmission1 has afirst box11 that houses themotor2, and asecond box12 that is externally fitted on thefirst box11. Thebody box10 also has athird box13 assembled on thefirst box11, and a fourth box14 (box) assembled on thesecond box12.

Thefirst box11 has a cylindricalsupport wall part111, and a flange shapedjunction part112 provided on oneend111aof thesupport wall part111.

In thefirst box11, thesupport wall part111 is provided facing along the rotation axis X of themotor2. Themotor2 is housed inside thesupport wall part111.

Thejunction part112 is provided facing orthogonal to the rotation axis X. Thejunction part112 is formed with a larger outer diameter than thesupport wall part111.

Thesecond box12 has a cylindricalperipheral wall part121, a flange shapedjunction part122 provided on oneend121aof theperipheral wall part121, and a flange shapedjunction part123 provided on anotherend121bof theperipheral wall part121.

Theperipheral wall part121 is formed with an inner diameter that can be externally fitted on thesupport wall part111 of thefirst box11.

Thefirst box11 and thesecond box12 are assembled to each other by theperipheral wall part121 of thesecond box12 being externally fitted on thesupport wall part111 of thefirst box11.

Thejunction part122 of the oneend121aside of theperipheral wall part121 abuts thejunction part112 of thefirst box11 from the rotation axis X direction. Thesejunction parts122,112 are linked to each other by bolts (not illustrated).

In thefirst box11, a plurality ofrecessed grooves111bare provided on the outer circumference of thesupport wall part111. The plurality of recessedgrooves111bare provided with a gap open in the rotation axis X direction. Each of the recessedgrooves111bis provided along the entire circumference in the circumferential direction around the rotation axis X.

Theperipheral wall part121 of thesecond box12 is externally fitted on thesupport wall part111 of thefirst box11. The openings of the recessedgrooves111bare closed by theperipheral wall part121. A plurality of cooling paths CP through which cooling water is circulated are formed between thesupport wall part111 and theperipheral wall part121.

At the outer circumference of thesupport wall part111 of thefirst box11,ring grooves111c,111care formed at both sides of the region in which the recessedgrooves111bare provided. Seal rings113,113 are externally engaged and attached to thering grooves111c,111c.

These seal rings113 are press fitted on the inner circumference of theperipheral wall part121 that is externally fitted on thesupport wall part111, and seal the gap between the outer circumference of thesupport wall part111 and the inner circumference of theperipheral wall part121.

On theother end121bof thesecond box12, awall part120 extending to the inner diameter side is provided. Thewall part120 is provided facing orthogonal to the rotation axis X. Anopening120ain which thedrive shaft9A is inserted is opened in the region intersecting the rotation axis X of thewall part120.

In thewall part120, a cylindricalmotor support unit125 that surrounds the opening120ais provided on themotor2 side (right side in the drawing) surface.

Themotor support unit125 is inserted inside acoil end253bdescribed later. Themotor support unit125 faces anend part21bof arotor core21 with a gap open in the rotation axis X direction.

In theperipheral wall part121 of thesecond box12, in the lower region in the vertical line direction with the mounted state of thepower transmission device1 in the vehicle as reference, the thickness in the radial direction is thicker than the upper region.

In this region that is thick in the radial direction, anoil reservoir128 is provided penetrating in the rotation axis X direction.

Theoil reservoir128 is connected via acommunication hole112ato anaxial oil passage138 provided in ajunction part132 of thethird box13. Thecommunication hole112ais provided in thejunction part112 of thefirst box11.

Thethird box13 has awall part130 that is orthogonal to the rotation axis X. Ajunction part132 that forms a ring shape seen from the rotation axis X direction is provided on the outer circumference part of thewall part130.

Seen from thefirst box11, thethird box13 is positioned on the opposite side (right side in the drawing) from thedifferential mechanism5. Thejunction part132 of thethird box13 is joined to thejunction part112 of thefirst box11 from the rotation axis X direction. Thethird box13 and thefirst box11 are linked to each other by bolts (not illustrated). In this state, in thefirst box11, the opening on thejunction part122 side (right side in the drawing) of thesupport wall part111 is blocked by thethird box13.

In thethird box13, aninsertion hole130aof thedrive shaft9A is provided in the center of thewall part130.

A lip seal RS is provided on the inner circumference of theinsertion hole130a. In the lip seal RS, a lip section (not illustrated) is in elastic contact with the outer circumference of thedrive shaft9A. The gap between the inner circumference of theinsertion hole130aand the outer circumference of thedrive shaft9A is sealed by the lip seal RS.

Aperipheral wall part131 that surrounds theinsertion hole130ais provided on the surface of thefirst box11 side (left side in the drawing) in thewall part130. Thedrive shaft9A is supported with a bearing B4 interposed on the inner circumference of theperipheral wall part131.

Seen from theperipheral wall part131, amotor support unit135 is provided on themotor2 side (left side in the drawing). Themotor support unit135 forms a tube shape that surrounds the rotation axis X with a gap open.

A cylindrical connectingwall136 is connected to the outer circumference of themotor support unit135. The connectingwall136 is formed with a larger outer diameter than theperipheral wall part131 of thewall part130 side (right side in the drawing). The connectingwall136 is provided facing along the rotation axis X, and extends in the direction separating from themotor2. The connectingwall136 connects themotor support unit135 and thewall part130 of thethird box13.

Themotor support unit135 is supported by thethird box13 with the connectingwall136 interposed. Oneend20aside of amotor shaft20 penetrates the inside of themotor support unit135 from themotor2 side to theperipheral wall part131 side.

A bearing B1 is supported on the inner circumference of themotor support unit135. The outer circumference of themotor shaft20 is supported by themotor support unit135 with the bearing B1 interposed.

The lip seal RS is provided on the position adjacent to the bearing B1.

In thethird box13, anoil hole136adescribed later is open at the inner circumference of the connectingwall136. Oil OL from theoil hole136ais made to flow into a space (internal space Sc) surrounded by the connectingwall136. The lip seal RS is provided to prevent the inflow of oil OL inside the connectingwall136 to themotor2 side.

Thefourth box14 has aperipheral wall part141 that surrounds the outer circumference of the planetary reduction gear4 and thedifferential mechanism5, and a flange shapedjunction part142 provided on the end part of thesecond box12 side in theperipheral wall part141.

Thefourth box14 is positioned at thedifferential mechanism5 side (left side in the drawing) seen from thesecond box12. Thejunction part142 of thefourth box14 is joined from the rotation axis X direction to thejunction part123 of thesecond box12. Thefourth box14 and thesecond box12 are linked to each other by bolts (not illustrated).

Inside thebody box10 of thepower transmission device1, a motor chamber Sa that houses themotor2 and a gear chamber Sb that houses the planetary reduction gear4 and thedifferential mechanism5 are formed.

The motor chamber Sa is formed between thewall part120 of thesecond box12 and thewall part130 of thethird box13 on the inside of thefirst box11.

The gear chamber Sb is formed between thewall part120 of thesecond box12 and theperipheral wall part141 of thefourth box14 on the inner diameter side of thefourth box14.

Aplate member8 is provided on the inside of the gear chamber Sb.

Theplate member8 is fixed to thefourth box14.

In theplate member8, the gear chamber Sb is partitioned into a first gear chamber Sb1 that houses the planetary reduction gear4 and thedifferential mechanism5, and a second gear chamber Sb2 that houses thepark lock mechanism3.

The second gear chamber Sb2 is positioned between the first gear chamber Sb1 and the motor chamber Sa in the rotation axis X direction.

Themotor2 has thecylindrical motor shaft20, thecylindrical rotor core21 externally fitted on themotor shaft20, and astator core25 that surrounds the outer circumference of therotor core21 with a gap open.

In themotor shaft20, bearings B1, B1 are externally fitted and fixed at both sides of therotor core21.

The bearing B1 positioned at oneend20aside (right side in the drawing) of themotor shaft20 seen from therotor core21 is supported on the inner circumference of themotor support unit135 of thethird box13. The bearing B1 positioned at theother end20bside is supported on the inner circumference of the cylindricalmotor support unit125 of thesecond box12.

Themotor support units135,125 are arranged facing with a gap open in the rotation axis X direction on the oneend part21aand theother end part21bof therotor core21 on the inner diameter side of coil ends253a,253bdescribed later.

Therotor core21 is formed by laminating a plurality of silicon steel sheets, and each of the silicon steel sheets is externally fitted on themotor shaft20 in a state where relative rotation with themotor shaft20 is regulated.

Seen from the rotation axis X direction of themotor shaft20, the silicon steel sheet has a ring shape. At the outer circumference side of the silicon steel sheet, N pole and S pole magnets (not illustrated) are provided alternately in the circumferential direction around the rotation axis X.

Thestator core25 surrounding the outer circumference of therotor core21 is formed by laminating a plurality of electromagnetic steel sheets. Thestator core25 is fixed to the inner circumference of the cylindricalsupport wall part111 of thefirst box11.

Each of the electromagnetic steel sheets has a ring-shapedyoke part251 fixed to the inner circumference of thesupport wall part111, and ateeth part252 projecting to therotor core21 side from the inner circumference of theyoke part251.

With the present embodiment, thestator core25 having a configuration in which a winding253 is distributed and wound across a plurality ofteeth parts252 is adopted. Thestator core25 has a longer length in the rotation axis X direction than therotor core21 by the amount of the coil ends253a,253bprojecting in the rotation axis X direction.

It is also possible to adopt the stator core of a configuration in which the windings are concentrically wound on each of the plurality ofteeth parts252 projecting to therotor core21 side.

The opening120ais provided in the wall part120 (motor support unit125) of thesecond box12. Theother end20bside of themotor shaft20 is positioned inside thefourth box14, penetrating the opening120aat thedifferential mechanism5 side (left side in the drawing).

Theother end20bof themotor shaft20 faces aside gear54A described later with a gap open in the rotation axis X direction on the inside of thefourth box14.

As shown inFIG.3, in themotor shaft20, astep201 is provided in a region positioned inside thefourth box14. Thestep201 is positioned in the vicinity of themotor support unit125. The lip seal RS supported on the inner circumference of themotor support unit125 is abutting the outer circumference of the region between thestep201 and the bearing B1.

The lip seal RS is partitioned into the motor chamber Sa that houses themotor2 and the gear chamber Sb inside thefourth box14.

The oil OL for lubricating the planetary reduction gear4 and thedifferential mechanism5 is sealed at the inner diameter side of the fourth box14 (seeFIG.2).

The lip seal RS is provided to prevent inflow of the oil OL to the motor chamber Sa.

As shown inFIG.3, in themotor shaft20, the region from thestep201 to the vicinity of theother end20bis a fitted part202 with a spline provided on the outer circumference.

The parking gear30 and asun gear41 are spline fitted on the outer circumference of the fitted part202.

In the parking gear30, one side surface of the parking gear30 in the rotation axis X direction abuts the step201 (right side in the drawing). One end410aof acylindrical base410 of thesun gear41 abuts the other side surface of the parking gear30 (left side in the drawing).

A nut N screwed onto theother end20bof themotor shaft20 is press fitted from the rotation axis X direction on theother end410bof thebase410.

Thesun gear41 and the parking gear30 are provided in a state sandwiched between the nut N and thestep201, without being able to rotate relatively to themotor shaft20.

Thesun gear41 hasteeth411 on the outer circumference of theother end20bside of themotor shaft20. A largediameter gear part431 of a steppedpinion gear43 engages with the outer circumference of theteeth411.

The stepped pinion gear43 (pinion gear) has the largediameter gear part431 that engages with thesun gear41, and a smalldiameter gear part432 with a smaller diameter than the largediameter gear part431.

The steppedpinion gear43 is a gear component in which the largediameter gear part431 and the smalldiameter gear part432 are provided integrally aligned in an axis line X1 direction parallel to the rotation axis X.

The largediameter gear part431 is formed with an outer diameter R1 greater than an outer diameter R2 of the smalldiameter gear part432.

The steppedpinion gear43 is provided facing along the axis line X1. In this state, the largediameter gear part431 is positioned at themotor2 side (right side in the drawing).

The outer circumference of the smalldiameter gear part432 is engaged with the inner circumference of aring gear42. Thering gear42 forms a ring shape that surrounds the rotation axis X with a gap open. A plurality ofengagement teeth421 projecting radially outward are provided on the outer circumference of thering gear42. The plurality ofengagement teeth421 have a plurality provided at prescribed intervals in the circumferential direction around the rotation axis X.

In thering gear42, theengagement teeth421 provided on the outer circumference are spline fitted toteeth146aprovided on asupport wall part146 of thefourth box14. In thering gear42, rotation around the rotation axis X is regulated by engaging with thesupport wall part146 as a ring gear support part.

The steppedpinion gear43 has a through hole430 penetrating the inner diameter side of the largediameter gear part431 and the smalldiameter gear part432 in the axis line X1 direction.

The steppedpinion gear43 is supported to be able to rotate on the outer circumference of apinion shaft44 penetrating the through hole430 with the needle bearings NB, NB interposed.

On the outer circumference of thepinion shaft44, a middle spacer MS is interposed between the needle bearing NB that supports the inner circumference of the largediameter gear part431 and the needle bearing NB that supports the inner circumference of the smalldiameter gear part432.

As shown inFIG.4, a shaft-internal oil passage440 is provided on the inside of thepinion shaft44. The shaft-internal oil passage440 penetrates from oneend44aof thepinion shaft44 to anotherend44balong the axis line X1.

Oil holes442,443 that communicate between the shaft-internal oil passage440 and the outer circumference of thepinion shaft44 are provided on thepinion shaft44.

Theoil hole443 opens in the region in which the needle bearing NB that supports the inner circumference of the largediameter gear part431 is provided.

Theoil hole442 opens in the region in which the needle bearing NB that supports the inner circumference of the smalldiameter gear part432 is provided.

In thepinion shaft44, the oil holes443,442 open inside the region in which the steppedpinion gear43 is externally fitted.

Furthermore, anintroduction path441 for introducing the oil OL into the shaft-internal oil passage440 is provided in thepinion shaft44.

In the outer circumference of thepinion shaft44, theintroduction path441 opens in the region positioned inside asupport hole71aof asecond case unit7 described later. Theintroduction path441 communicates between the shaft-internal oil passage440 and the outer circumference of thepinion shaft44.

A case-internal oil passage781 is opened on the inner circumference of thesupport hole71a. The case-internal oil passage781 communicates between the inner circumference of aguide unit78 projecting from abase71 of thesecond case unit7 and the inner circumference of thesupport hole71a.

In the cross section view along the axis line X1, the case-internal oil passage781 is inclined with respect to the axis line X1. The case-internal oil passage781 is inclined facing toward aslit710 provided in the base71 as it faces the rotation axis X side.

The oil OL scooped up by adifferential case50 described later flows into the case-internal oil passage781. The oil OL that moves to the outer diameter side by centrifugal force due to rotation of thedifferential case50 also flows into the case-internal oil passage781.

The oil OL that flows into theintroduction path441 from the case-internal oil passage781 flows into the shaft-internal oil passage440 of thepinion shaft44. The oil OL that flows into the shaft-internal oil passage440 is discharged radially outward from the oil holes442,443. The oil OL discharged from the oil holes442,443 lubricates the needle bearing NB externally fitted on thepinion shaft44.

In thepinion shaft44, a throughhole444 is provided more to theother end44bside than the region in which theintroduction path441 is provided. The throughhole444 penetrates thepinion shaft44 in the diameter line direction.

Thepinion shaft44 is provided so that the throughhole444 and aninsertion hole782 of thesecond case unit7 described later are in phase around the axis line X1. A positioning pin P inserted in theinsertion hole782 penetrates the throughhole444 of thepinion shaft44. As a result, thepinion shaft44 is supported on thesecond case unit7 side in a state with rotation around the axis line X1 regulated.

As shown inFIG.4, on the oneend44aside in the lengthwise direction of thepinion shaft44, a region projecting from the steppedpinion gear43 is afirst shaft part445. Thefirst shaft part445 is supported by asupport hole61aprovided in afirst case unit6 of thedifferential case50.

At theother end44bside in the lengthwise direction of thepinion shaft44, the region projecting from the steppedpinion gear43 is asecond shaft part446. Thesecond shaft part446 is supported by thesupport hole71aprovided in thesecond case unit7 of thedifferential case50.

Here, thefirst shaft part445 means a region of the oneend44aside in which the steppedpinion gear43 is not externally fitted in thepinion shaft44. Thesecond shaft part446 means a region of theother end44bside in which the steppedpinion gear43 is not externally fitted in thepinion shaft44.

In thepinion shaft44, the length of the axis line X1 direction is longer for thesecond shaft part446 than thefirst shaft part445.

Following, the main configuration of thedifferential mechanism5 is explained.

FIG.5 is a perspective view around thedifferential case50 of thedifferential mechanism5.

FIG.6 is an exploded perspective view around thedifferential case50 of thedifferential mechanism5.

As shown inFIG.4 toFIG.6, thedifferential case50 as a case houses thedifferential mechanism5. Thedifferential case50 is formed by assembling thefirst case unit6 and thesecond case unit7 in the rotation axis X direction. In the present embodiment, thefirst case unit6 and thesecond case unit7 of thedifferential case50 have a function as carriers that support thepinion shaft44 of the planetary reduction gear4.

As shown inFIG.6, three pinion mate gears52 and threepinion mate shafts51 are provided between thefirst case unit6 and thesecond case unit7 of thedifferential case50. Thepinion mate shafts51 function as support shafts that support the pinion mate gears52.

Thepinion mate shafts51 are provided at equal intervals in the circumferential direction around the rotation axis X (seeFIG.6).

The end part of the inner diameter side of eachpinion mate shaft51 is linked to acommon linking part510.

Onepinion mate gear52 each is externally fitted on thepinion mate shafts51. Eachpinion mate gear52 is in contact with the linkingpart510 from the radial outward side of the rotation axis X.

Each of the pinion mate gears52 in this state is supported to be rotatable on thepinion mate shaft51.

As shown inFIG.4, aspherical washer53 is externally fitted on thepinion mate shaft51. Thespherical washer53 is in contact with the spherical outer circumference of thepinion mate gear52.

In thedifferential case50, theside gear54A is positioned at one side of the linkingpart510 in the rotation axis X direction, and aside gear54B is positioned at the other side. Theside gear54A is supported to be rotatable on thefirst case unit6. Theside gear54B is supported to be rotatable on thesecond case unit7.

Theside gear54A is engaged to the three pinion mate gears52 from one side in the rotation axis X direction. Theside gear54B engages with the three pinion mate gears52 from the other side in the rotation axis X direction.

FromFIG.7 toFIG.10 are drawings for explaining thefirst case unit6.

FIG.7 is a perspective view of thefirst case unit6 seen from thesecond case unit7 side.

FIG.8 is a plan view of thefirst case unit6 seen from thesecond case unit7 side.

FIG.9 is a schematic diagram of the A-A cross section inFIG.8.FIG.9 shows the arrangement of thepinion mate shaft51 and thepinion mate gear52 using virtual lines.

FIG.10 is a schematic diagram of the A-A cross section inFIG.8.FIG.10 shows the arrangement of theside gear54A, the steppedpinion gear43, and thedrive shaft9A using virtual lines while omitting an illustration of a linkingbeam62 of the paper surface back side.

As shown inFIG.7 andFIG.8, thefirst case unit6 has a ring-shapedbase61. Thebase61 is a plate shaped member having a thickness W61 in the rotation axis X direction.

As shown inFIG.9 andFIG.10, anopening60 is provided in the center of thebase61. Acylinder wall part611 that surrounds theopening60 is provided on the surface on the side opposite to the second case unit7 (right side in the drawing) in thebase61. The outer circumference of thecylinder wall part611 is supported by theplate member8 with a bearing B3 interposed (seeFIG.2).

Three linkingbeams62 extending to thesecond case unit7 side are provided on the surface of thesecond case unit7 side (left side in the drawing) in thebase61.

The linking beams62 are provided at equal intervals in the circumferential direction around the rotation axis X (seeFIG.7 andFIG.8).

The linking beams62 have a base63 orthogonal to thebase61 and a linkingpart64 that is wider than thebase63.

As shown inFIG.9, atip surface64aof the linkingpart64 is a flat surface orthogonal to the rotation axis X. Asupport groove65 for supporting thepinion mate shaft51 is provided on thetip surface64a.

As shown inFIG.8, thesupport groove65 seen from the rotation axis X direction is formed in a straight line along a radius line L of the ring-shapedbase61. Thesupport groove65 crosses the center of the linkingpart64 from the inner diameter side to the outer diameter side in the circumferential direction around the rotation axis X.

As shown inFIG.9 andFIG.10, thesupport groove65 forms a semicircle shape along the outer diameter of thepinion mate shaft51. Thesupport groove65 is formed at a depth that can house half of the cylindricalpinion mate shaft51. Specifically, thesupport groove65 is formed at a depth corresponding to half the diameter Da of the pinion mate shaft51 (=Da/2).

Anarc part641 is formed in a shape along the outer circumference of thepinion mate gear52 on the inner diameter side (rotation axis X side) of the linkingpart64.

In thearc part641, the outer circumference of thepinion mate gear52 is supported with thespherical washer53 interposed.

In thearc part641, anoil groove642 is provided facing along the radius line L noted above. Theoil groove642 is provided in a range from thesupport groove65 of thepinion mate shaft51 to agear support part66 fixed to the inner circumference of the linkingpart64.

Thegear support part66 is connected to the boundary of thebase63 and the linkingpart64. Thegear support part66 is provided facing orthogonal to the rotation axis X. Thegear support part66 has a throughhole660 at the center.

As shown inFIG.8, the outer circumference of thegear support part66 is connected to the inner circumference of the three linkingparts64. In this state, the center of the throughhole660 is positioned on the rotation axis X.

As shown inFIG.9 andFIG.10, in thegear support part66, arecess661 surrounding the throughhole660 is provided on the surface of the side opposite to the base61 (left side in the drawing). In therecess661, a ring-shapedwasher55 that supports the back surface of theside gear54A is housed.

A cylindricalcylinder wall part541 is provided on the back surface of theside gear54A. Thewasher55 is externally fitted on thecylinder wall part541.

Seen from the rotation axis X direction, threeoil grooves662 are provided on the surface of therecess661 side in thegear support part66. Theoil grooves662 are provided at prescribed intervals in the circumferential direction around the rotation axis X.

Theoil groove662 extends from the inner circumference of thegear support part66 to the outer circumference along the radius line L noted above. Theoil groove662 is in contact with theoil groove642 on thearc part641 side noted above.

As shown inFIG.7 andFIG.8, the support holes61aof thepinion shaft44 are open on thebase61. The support holes61aare open at the region between the linkingbeams62,62 arranged at prescribed intervals in the circumferential direction around the rotation axis X.

Aboss part616 surrounding thesupport hole61ais provided on thebase61. A washer We (seeFIG.10) externally fitted on thepinion shaft44 is in contact with theboss part616 from the rotation axis X direction.

In thebase61, anoil groove617 is provided in the range from the center opening60 to theboss part616.

As shown inFIG.8, theoil groove617 is formed in a tapered shape in which the circumferential direction width around the rotation axis X becomes narrower as it approaches theboss part616. Theoil groove617 is connected to anoil groove618 provided on theboss part616.

In the linkingpart64, bolt holes67,67 are provided at both sides of thesupport groove65.

A linkingpart74 of thesecond case unit7 side is joined from the rotation axis X direction to the linkingpart64 of thefirst case unit6. Thefirst case unit6 and thesecond case unit7 are joined to each other by the bolts B that penetrate the linkingpart74 of thesecond case unit7 side being screwed into bolt holes67,67.

FIG.11 toFIG.16 are drawings for explaining thesecond case unit7.

FIG.11 is a perspective view of thesecond case unit7 seen from thefirst case unit6 side.

FIG.12 is a plan view of thesecond case unit7 seen from thefirst case unit6 side.

FIG.13 is a schematic diagram of the A-A cross section inFIG.12.FIG.13 shows the arrangement of thepinion mate shaft51 and thepinion mate gear52 using virtual lines.

FIG.14 is a schematic diagram of the A-A cross section inFIG.12.FIG.14 shows the arrangement of theside gear54B, the steppedpinion gear43, and thedrive shaft9B using virtual lines while omitting an illustration of the linkingpart74 at the paper surface back side.

FIG.15 is a perspective view of thesecond case unit7 seen from the side opposite to thefirst case unit6.

FIG.16 is a plan view of thesecond case unit7 seen from the side opposite to thefirst case unit6.

As shown inFIG.13 andFIG.14, thesecond case unit7 has the ring-shapedbase71.

Thebase71 is a plate shaped member having a thickness W71 in the rotation axis X direction.

A throughhole70 that penetrates the base71 in the thickness direction is provided at the center of thebase71.

Acylinder wall part72 that surrounds the throughhole70 and aperipheral wall part73 that surrounds thecylinder wall part72 with a prescribed gap are provided at the surface on the side opposite to the first case unit6 (left side in the drawing) in thebase71.

Aprojection73athat projects to the rotation axis X side is provided at the tip of theperipheral wall part73. Theprojection73ais provided across the entire circumference in the circumferential direction around the rotation axis X.

As shown inFIG.16, threesupport holes71aof thepinion shaft44 are open at the outer diameter side of theperipheral wall part73. The support holes71aare provided at prescribed intervals in the circumferential direction around the rotation axis X.

Threeslits710 penetrating the base71 in the thickness direction are provided on the inner diameter side ofperipheral wall part73.

Seen from the rotation axis X direction, theslits710 form an arc shape along the inner circumference of theperipheral wall part73. Theslits710 are formed in a prescribed angle range in the circumferential direction around the rotation axis X.

Theslits710 in thesecond case unit7 are provided at prescribed intervals in the circumferential direction around the rotation axis X. Each of theslits710 is provided crossing the inner diameter side of thesupport hole71ain the circumferential direction around the rotation axis X.

Three projectingwalls711 projecting to the paper surface front side are provided betweenadjacent slits710,710 in the circumferential direction around the rotation axis. The projectingwalls711 extend in a straight line in the radial direction of the rotation axis X. The projectingwalls711 are provided connecting theperipheral wall part73 of the outer diameter side and thecylinder wall part72 of the inner diameter side.

The projectingwalls711 are provided at prescribed intervals in the circumferential direction around the rotation axis X. The projectingwalls711 are provided with a phase shift of approximately 45 degrees in the circumferential direction around the rotation axis X with respect to theslits710.

Bolt housing parts76,76 recessed at the paper surface back side are provided between support holes71a,71aadjacent in the circumferential direction around the rotation axis X at the outer diameter side ofperipheral wall part73. Thesebolt housing parts76,76 are provided in a positional relationship that is symmetrical with the radius line L sandwiched between. Thebolt housing parts76 open at anouter circumference71cof thebase71.

Bolt insertion holes77 open at the inside of thebolt housing parts76. The insertion holes77 penetrate the base71 in the thickness direction (rotation axis X direction).

As shown inFIG.11 andFIG.12, the three linkingparts74 projecting to thefirst case unit6 side are provided on the surface of thefirst case unit6 side (right side in the drawing) in thebase71.

The linkingparts74 are provided at equal intervals in the circumferential direction around the rotation axis X. The linkingparts74 are formed at a width W7 in the same circumferential direction as the linkingparts64 of thefirst case unit6 side.

As shown inFIG.13, atip surface74aof the linkingpart74 is a flat surface orthogonal to the rotation axis X. Asupport groove75 for supporting thepinion mate shaft51 is provided on thetip surface74a.

As shown inFIG.12, thesupport groove75 seen from the rotation axis X direction is formed in a straight line along the radius line L of thebase71. Thesupport groove75 is formed crossing the linkingpart74 from the inner diameter side to the outer diameter side.

As shown inFIG.5, thesupport groove75 forms a semicircle shape along the outer diameter of thepinion mate shaft51.

As shown inFIG.13, thesupport groove75 is formed at a depth capable of housing half of the cylindricalpinion mate shaft51. Specifically, thesupport groove75 is formed at a depth corresponding to half the diameter Da (=Da/2) of thepinion mate shaft51.

Anarc part741 is provided along the outer circumference of thepinion mate gear52 on the inner diameter side (rotation axis X side) of the linkingpart74.

In thearc part741, the outer circumference of thepinion mate gear52 is supported with thespherical washer53 interposed (seeFIG.13 andFIG.14).

Anoil groove742 facing along the radius line L noted above is provided in thearc part741. Theoil groove742 is provided in a range from thesupport groove75 of thepinion mate shaft51 to the base71 positioned at the inner circumference of the linkingpart74.

Theoil groove742 connects with anoil groove712 provided in afront surface71bof thebase71. Theoil groove712 seen from the rotation axis X direction is provided along the radius line L, and is formed to the throughhole70 provided in thebase71.

The ring-shapedwasher55 that supports the back surface of theside gear54B is placed on thefront surface71bof thebase71. A cylindricalcylinder wall part540 is provided on the back surface of theside gear54B. Thewasher55 is externally fitted on thecylinder wall part540.

Anoil groove721 is formed at the position intersecting theoil groove712 on the inner circumference of thecylinder wall part72 surrounding the thoughhole70. Theoil groove721 is provided facing along the rotation axis X across the entire length of the rotation axis X direction of thecylinder wall part72 on the inner circumference of thecylinder wall part72.

As shown inFIG.11 andFIG.12, theguide unit78 is provided between linkingparts74,74 adjacent in the circumferential direction around the rotation axis X at thebase71 of thesecond case unit7. Theguide unit78 projects to thefirst case unit6 side (paper surface front side).

Theguide unit78 forms a cylinder seen from the rotation axis X direction. Theguide unit78 surrounds thesupport hole71aprovided in thebase71. The outer circumference part of theguide unit78 is cut along theouter circumference71cof thebase71.

As shown inFIG.13 andFIG.14, in the cross section view along the axis line X1, thepinion shaft44 is inserted from thefirst case unit6 side in thesupport hole71aof theguide unit78. Thepinion shaft44 is positioned by the positioning pin P in a state with the rotation around the axis line X1 regulated.

In this state, the smalldiameter gear part432 of the steppedpinion gear43 externally fitted on thepinion shaft44 abuts theguide unit78 from the axis line X1 direction with the washer We sandwiched between.

As shown inFIG.4, in thedifferential case50, a bearing B2 is externally fitted on thecylinder wall part72 of thesecond case unit7. The bearing B2 that is externally fitted on thecylinder wall part72 is held by asupport unit145 of thefourth box14. Thecylinder wall part72 of thedifferential case50 is supported to be rotatable with thefourth box14 with the bearing B2 interposed.

Thedrive shaft9B that penetrates anopening145aof thefourth box14 is inserted from the rotation axis X direction in thesupport unit145. Thedrive shaft9B is supported to be rotatable with thesupport unit145.

The lip seal RS is fixed to the inner circumference of the opening145a. The lip section (not illustrated) of the lip seal RS is elastically in contact with the outer circumference of thecylinder wall part540 of theside gear54B externally fitted on thedrive shaft9B. As a result, the gap between the outer circumference of thecylinder wall part540 of theside gear54B and the inner circumference of the opening145ais sealed.

Thefirst case unit6 of thedifferential case50 is supported by theplate member8 with the bearing B3 that is externally fitted on thecylinder wall part611 interposed (seeFIG.2).

Thedrive shaft9A that penetrates theinsertion hole130aof thethird box13 is inserted from the rotation axis direction inside thefirst case unit6.

Thedrive shaft9A is provided crossing themotor shaft20 of themotor2 and the inner diameter side of thesun gear41 of the planetary reduction gear4 in the rotation axis X direction.

As shown inFIG.4, in the interior of thedifferential case50, side gears54A,54B are spline fitted at the outer circumference of the tip end part of the drive shafts9 (9A,9B). The side gears54A,54B and drive shafts9 (9A,9B) are linked to be able to rotate integrally around the rotation axis X.

In this state, the side gears54A,54B are arranged facing with a gap open in the rotation axis X direction. The linkingpart510 of thepinion mate shaft51 is positioned between the side gears54A,54B.

In the present embodiment, the total of threepinion mate shafts51 extend radially outside from the linkingpart510. Apinion mate gear52 is supported on each of thepinion mate shafts51. The pinion mate gears52 are assembled in a state with the teeth mutually engaged on theside gear54A positioned at one side in the rotation axis X direction and theside gear54B positioned at the other side.

As shown inFIG.2, the oil OL for lubrication is retained inside thefourth box14. The bottom side of thedifferential case50 is positioned within the retained oil OL.

In the present embodiment, when the linkingbeam62 is positioned at the bottommost side, the oil OL is retained up to the height at which thelinking beam62 is positioned within the oil OL.

When the output rotation of themotor2 is transmitted, the retained oil OL is scooped up by thedifferential case50 that rotates around the rotation axis X.

FIG.17 toFIG.25 are drawings for explaining theoil catch unit15.

FIG.17 is a plan view of thefourth box14 seen from thethird box13 side.

FIG.18 is a perspective view of theoil catch unit15 shown inFIG.17 seen from diagonally above.

FIG.19 is a plan view of thefourth box14 seen from thethird box13 side.FIG.19 is a drawing showing the state with thedifferential case50 arranged.

FIG.20 is a perspective view of theoil catch unit15 shown inFIG.19 seen from diagonally above.

FIG.21 is a schematic diagram of the A-A cross section inFIG.19.

FIG.22 is a schematic diagram for explaining the positional relationship between theoil catch unit15 and the differential case50 (first case unit6, second case unit7) when thepower transmission device1 is seen from above.

FIG.23 is a drawing of acatch unit153 seen from above.

FIG.24 is a cross section view of A-A inFIG.23, and is a drawing for explaining the incline of aninclined part156.

FIG.25 is a cross section view of B-B inFIG.23, and is a drawing for explaining the incline of aninclined part157. InFIG.24 andFIG.25, the incline of theinclined part156 and theinclined part157 are shown exaggerated, and parts other than the inclined parts are omitted as appropriate.

InFIG.17 andFIG.19, to make the position of thejunction part142 of thefourth box14 and thesupport wall part146 clear, these are shown marked by cross hatching.

As shown inFIG.17, thesupport wall part146 surrounding the center opening145awith a prescribed gap is provided in thefourth box14 seen from the rotation axis X direction. The inside (rotation axis X) side of thesupport wall part146 is ahousing unit140 of the differential case50 (seeFIG.19).

A space of theoil catch unit15 and a space of abreather chamber16 are formed above a horizontal line HL that passes through the rotation axis X inside thefourth box14. Here, the horizontal line HL is the horizontal line HL with the installation state of thepower transmission device1 in the vehicle as reference. Seen from the rotation axis X direction, the horizontal line HL is orthogonal to the rotation axis X.

In thesupport wall part146 of thefourth box14, acommunication port147 that communicates between theoil catch unit15 and thehousing unit140 of thedifferential case50 is provided in the region intersecting a vertical line VL. Thecommunication port147 is formed as a notch in thesupport wall part146 as a ring gear support part.

As shown inFIG.17, theoil catch unit15 and thebreather chamber16 are respectively positioned at one side (left side in the drawing) and the other side (right side in the drawing) sandwiching the vertical line VL that is orthogonal to the rotation axis X.

Theoil catch unit15 is arranged at a position offset from the vertical line VL passing through the rotation center of the differential case50 (rotation axis X). As shown inFIG.22, when viewing theoil catch unit15 from above, theoil catch unit15 is arranged at a position offset from directly above thedifferential case50.

Here, the vertical line VL is a vertical line VL with the installation state of thepower transmission device1 in the vehicle as reference. Seen from the rotation axis X direction, the vertical line VL is orthogonal to the rotation axis X and the horizontal line HL.

As shown inFIG.18, theoil catch unit15 is formed extending to the paper surface back side from thesupport wall part146. Asupport stand151 as a shelf part projecting to the paper surface front side is provided on the bottom edge of theoil catch unit15. Thesupport stand151 is provided on the paper surface front side from thesupport wall part146, and in a range to the paper surface back side from thejunction part142 of thefourth box14.

As shown inFIG.17, seen from the rotation axis X direction, thecommunication port147 is formed with a portion of thesupport wall part146 cut out on the vertical line VL side (right side in the drawing) of theoil catch unit15. Thecommunication port147 communicates between theoil catch unit15 and thehousing unit140 of thedifferential case50. By thecommunication port147 being formed, thesupport wall part146 forms a C shape when seen from the rotation axis X direction.

Seen from the rotation axis X direction, thecommunication port147 is provided in a range crossing the vertical line VL from thebreather chamber16 side (right side in the drawing) to theoil catch unit15 side (left side in the drawing).

Thecommunication port147 is provided at a position adjacent to the support stand151 provided on theoil catch unit15 in the circumferential direction around the rotation axis X. As a result, the oil OL scooped up by thedifferential case50 more easily enters the support stand151 from thecommunication port147.

As shown inFIG.19, in the present embodiment, during forward travel of the vehicle in which thepower transmission device1 is mounted, seen from thethird box13 side, thedifferential case50 rotates in the counterclockwise direction CCW around the rotation axis X.

For that reason, theoil catch unit15 is positioned at the downstream side in the rotation direction of thedifferential case50. For the width in the circumferential direction of thecommunication port147, the left side sandwiching the vertical line VL is wider than the right side. The left side sandwiching the vertical line VL is at the downstream side in the rotation direction of thedifferential case50, and the right side is the upstream side. As a result, much of the oil OL scooped up by thedifferential case50 rotating around the rotation axis X is made to be able to flow into theoil catch unit15.

Furthermore, as shown inFIG.22, the outer circumference position of the rotational orbit of asecond shaft part446 and the outer circumference position of the rotational orbit of the largediameter gear part431 are offset in the radial direction of the rotation axis X. The outer circumference position of the rotational orbit of thesecond shaft part446 is positioned more to the inner diameter side than the outer circumference position of the rotational orbit of the largediameter gear part431. For that reason, there is a spatial margin at the outer diameter side of thesecond shaft part446. By providing theoil catch unit15 using this space, it is possible to effectively use the space inside thebody box10.

Also, thesecond shaft part446 projects to the back side of the smalldiameter gear part432 seen from themotor2. The peripheral member of the second shaft part446 (e.g. the guide unit58 of thedifferential case50 that supports the second shaft part446) is at a position near theoil catch unit15.

Thus, it is possible to smoothly perform supplying of the oil OL (lubricating oil) from that peripheral member to theoil catch unit15.

As shown inFIG.18, anoil hole151athat is open facing upward is provided at the back side of thesupport stand151. Theoil hole151aextends from the end part of the outer diameter side open at the top surface of the support stand151 to the inner diameter side inside thefourth box14. The end part of the inner diameter side of theoil hole151ais open on the inner circumference of thesupport unit145.

As shown inFIG.2, the end part of the inner diameter side of theoil hole151ain thesupport unit145 is open between the lip seal RS and the bearing B2.

As shown inFIG.20, anoil guide152 is placed on thesupport stand151. Theoil guide152 is provided as a catch member for the oil OL on the top part of the support stand151 (shelf part). Theoil guide152 has acatch unit153, and aguide unit154 extending from thecatch unit153 to thefirst box11 side (paper surface front side).

As shown inFIG.22, seen from above, thesupport stand151 is provided radially outside the rotation axis X, at a position partially overlapping the differential case50 (first case unit6, second case unit7), and to avoid interference with the stepped pinion gear43 (large diameter gear part431).

Seen from the radial direction of the rotation axis X, thecatch unit153 is provided at a position overlapping thesecond shaft part446 of thepinion shaft44. Furthermore, theguide unit154 is provided at a position where thefirst shaft part445 of thepinion shaft44 and the largediameter gear part431 overlap.

For that reason, when thedifferential case50 rotates around the rotation axis X, the oil OL scooped up by thedifferential case50 moves toward thecatch unit153 and theguide unit154 side.

As shown inFIG.23, thecatch unit153 is configured from theinclined part156 as a second inclined surface and theinclined part157 as a first inclined surface. Theinclined part156 is positioned at the back side of the support stand151 (upper side inFIG.22) and is connected to theoil hole151a. Theinclined part157 is positioned at the front side of the support stand151 (lower side ofFIG.22) and is connected to theguide unit154. Theinclined part157 communicates with theinclined part156 at oneend157a.

Theinclined part156 extends from oneend156aconnected to theoil hole151atoward anotherend156bin the direction orthogonal to the rotation axis X. As shown inFIG.24, the surface of theinclined part156 is inclined downward facing the oneend156afrom theother end156b.

As shown inFIG.23, theinclined part157 extends from the oneend157atoward anotherend157bin the direction along the rotation axis X. The oneend157aof theinclined part157 communicates with theinclined part156, and theother end157bis connected to theguide unit154. As shown inFIG.25, the surface of theinclined part157 is inclined downward from the oneend157atoward theother end157b.

As shown inFIG.20, awall part153astands on the outer circumference edge of theinclined part156 and theinclined part157 of thecatch unit153. Thewall part153aextends in the direction separating from the support stand151 (upward). A portion of the oil OL caught by thecatch unit153 is held and retained in theoil guide152 by thewall part153a.

The surface of theinclined part156 and theinclined part157 is each inclined. As a result, as shown inFIG.22, a portion of the oil OL caught by theinclined part156 flows toward theoil hole151aaccording to gravity. A portion of the oil OL caught by theinclined part157 flows toward theguide unit154 according to gravity.

As shown inFIG.23, anotch part155 is provided in thewall part153aextending from the oneend156aof theinclined part156.

Thenotch part155 is provided in a region facing theoil hole151a. A portion of the oil OL that flows toward theoil hole151ais discharged from thenotch part155 part toward theoil hole151a. Specifically, thenotch part155 acts as an introduction port to guide the oil OL to theoil hole151a.

Here, as shown inFIG.24 andFIG.25, an inclination angle α with respect to the horizontal line HL is smaller than an inclination angle β with respect to the horizontal line HL of theinclined part157. Specifically, theinclined part156 has a gentler incline than theinclined part157. The opening surface of theoil hole151ais smaller than the surface of theguide unit154. For that reason, the oil discharge amount of theoil hole151ais smaller than that of theguide unit154. For that reason, in the embodiment, the incline of theinclined part156 connected to theoil hole151ais made to be gentle, suppressing the amount of oil OL flowing to theoil hole151a. By matching the amount of oil OL flowing into theoil hole151ato the discharge amount of the oil OL from theoil hole151a, it is possible to keep a suitable amount of the oil OL retained in thecatch unit153.

Theguide unit154 is inclined downward as it separates from thecatch unit153. As shown inFIG.20,wall parts154a,154aare provided at both sides in the width direction of theguide unit154. Thewall parts154a,154aare provided across the entire length in the lengthwise direction of theguide unit154. Thewall parts154a,154aare connected to thewall part153athat surrounds the outer circumference of thecatch unit153.

As shown inFIG.23, a portion of the oil OL retained in theinclined part157 of thecatch unit153 is discharged to theguide unit154 side. Specifically, theguide unit154 acts as a branch port and branches a portion of the oil OL retained in thecatch unit153 and guides it to a location other than theoil hole151a.

As shown inFIG.21, in theguide unit154, the position that avoids interference with thedifferential case50 extends to thesecond box12 side. Atip154bof theguide unit154 faces a throughhole126aprovided on thewall part120 of thesecond box12 with a gap open in the rotation axis X direction.

Aboss part126 that surrounds the throughhole126ais provided on the outer circumference of thewall part120. One end of apipe127 is fitted into theboss part126 from the rotation axis X direction.

Thepipe127 passes through the outside of thesecond box12 to thethird box13. The other end of thepipe127 communicates with theoil hole136aprovided in thecylindrical connecting wall136 of the third box13 (seeFIG.2).

A portion of the oil OL scooped up by thedifferential case50 rotating around the rotation axis X reaches theoil catch unit15. The oil OL passes through theguide unit154 and thepipe127, and is supplied to the internal space Sc of the connectingwall136.

Aradial oil passage137 that communicates with the internal space Sc is provided in thethird box13.

Theradial oil passage137 extends radially downward from the internal space Sc. Theradial oil passage137 communicates with theaxial oil passage138 provided inside thejunction part132.

Theaxil oil passage138 connects with theoil reservoir128 provided at the bottom of thesecond box12 via thecommunication hole112aprovided in thejunction part112 of thefirst box11.

Theoil reservoir128 penetrates inside theperipheral wall part121 in the rotation axis X direction. Theoil reservoir128 connects with the second gear chamber Sb2 provided in thefourth box14.

The operation of thepower transmission device1 of this configuration is explained.

As shown inFIG.1, in thepower transmission device1, the planetary reduction gear4, thedifferential device5, and the drive shafts9 (9A,9B) are provided along the transmission route of the output rotation of themotor2.

As shown inFIG.2, when therotor core21 rotates around the rotation axis X by driving of themotor2, the rotation is inputted to thesun gear41 of the planetary reduction gear4 via themotor shaft20 that rotates integrally with therotor core21.

As shown inFIG.3, with the planetary reduction gear4, thesun gear41 serves as the input unit of the output rotation of themotor2. Thedifferential case50 that supports the steppedpinion gear43 serves as the output unit of the inputted rotation.

When thesun gear41 rotates around the rotation axis X by the inputted rotation, the stepped pinion gear43 (largediameter gear part431, small diameter gear part432) rotates around the axis line X1 by the rotation inputted from thesun gear41 side.

Here, the smalldiameter gear part432 of the steppedpinion gear43 is engaged with thering gear42 fixed to the inner circumference of thefourth box14. For that reason, the steppedpinion gear43 revolves around the rotation axis X while auto-rotating around the axis line X1. The rotation axis X is the revolution center of the stepped pinion gear43 (pinion gear).

Here, with the steppedpinion gear43, the outer diameter R2 of the smalldiameter gear part432 is smaller than the outer diameter R1 of the large diameter gear part431 (seeFIG.3).

By doing this, the differential case50 (first case unit6, second case unit7) that supports the steppedpinion gear43 rotates around the rotation axis X at a rotation speed lower than the rotation inputted from themotor2 side.

For that reason, the rotation inputted to thesun gear41 of the planetary reduction gear4 is significantly reduced by the steppedpinion gear43. The reduced rotation is outputted to the differential case50 (differential mechanism5).

By thedifferential case50 rotating around the rotation axis X by the inputted rotation, inside thedifferential case50, the drive shafts9 (9A,9B) that engage with thepinion mate gear52 rotate around the rotation axis X. As a result, drive wheels (not illustrated) at the left and right of the vehicle in which thepower transmission device1 is mounted rotate by the transmitted rotational drive power.

As shown inFIG.2, the oil OL for lubrication is retained inside thefourth box14. For that reason, the retained oil OL is scooped up by thedifferential case50 rotating around the rotation axis X during transmission of the output rotation of themotor2.

The engagement part between thesun gear41 and the largediameter gear part431, the engagement part between the smalldiameter gear part432 and thering gear42, and the engagement part between thepinion mate gear52 and the side gears54A,54B are lubricated by the scooped-up oil OL.

As shown inFIG.19, thedifferential case50 seen from thethird box13 side rotates in the counterclockwise direction CCW around the rotation axis X.

Theoil catch unit15 is provided on the top part of thefourth box14. Theoil catch unit15 is positioned at the downstream side in the rotation direction of thedifferential case50. Much of the oil OL scooped up by thedifferential case50 flows into theoil catch unit15.

As shown inFIG.22, theoil guide152 mounted on thesupport stand151 is provided in theoil catch unit15.

Theguide unit154 and thecatch unit153 of theoil guide152 are positioned at the radial outside of thefirst case unit6 of thedifferential case50 and the radial outside of thesecond case unit7 of thedifferential case50.

For that reason, much of the oil that is scooped up by thedifferential case50 and flows into theoil catch unit15 is captured by theoil guide152.

A portion of the oil OL captured by theinclined part156 of theoil guide152 flows along the incline to theoil hole151aside. The oil OL is discharged from thenotch part155 provided in thewall part153a, and flows into theoil hole151afor which one end is opened on the top surface of thesupport stand151.

The end part of the inner diameter side of theoil hole151ais open at the inner circumference of the support unit145 (seeFIG.2). For that reason, the oil OL that flows into theoil hole151ais discharged to a gap Rx between the inner circumference of thesupport unit145 of thefourth box14 and thecylinder wall part540 of theside gear54B.

A portion of the oil OL discharged to the gap Rx lubricates the bearing B2 supported by thesupport unit145. The oil OL that lubricates the bearing B2 moves to the outer diameter side by the centrifugal force by rotation of thedifferential case50. On the outer diameter side of thedifferential case50, theslit710 is provided along the inner circumference of theperipheral wall part73. Further movement of the oil OL to the outer diameter side is obstructed by theperipheral wall part73. The oil OL passes through theslit710 to thefirst case unit6 side.

At thefirst case unit6 side of theslit710, the case-internal oil passage781 is open in the inner circumference of theguide unit78. A portion of the oil OL that passes through theslit710 flows inside the case-internal oil passage781 by the centrifugal force by the rotation of thedifferential case50.

The oil OL that flows into the case-internal oil passage781 passes through theintroduction path441 and flows into the shaft-internal oil passage440 of thepinion shaft44. The oil OL that flows into the shaft-internal oil passage440 is discharged radially outside from the oil holes442,443. The discharged oil OL lubricates the needle bearing NB externally fitted on thepinion shaft44.

Furthermore, a portion of the oil OL discharged to the gap Rx passes through theoil groove721 provided on the inner circumference of thecylinder wall part72 of thesecond case unit7 as shown inFIG.13 andFIG.14. The oil OL that passes through theoil groove721 is supplied to thewasher55 that supports the back surface of theside gear54B and lubricates thewasher55.

Furthermore, the oil OL passes through theoil groove712 provided in thebase71 of thesecond case unit7 and theoil groove742 provided in thearc part741. The oil OL that passes through theoil groove742 is supplied to thespherical washer53 that supports the back surface of thepinion mate gear52 and lubricates thespherical washer53.

Also, as shown inFIG.22, a portion of the oil OL captured by theinclined part157 of theoil guide152 of theoil catch unit15 flows along the incline to theguide unit154 side. The oil OL further flows along the incline of theguide unit154. As shown inFIG.21, thetip154bof theguide unit154 faces the throughhole126aprovided in thewall part120 of thesecond box12 with a gap open in the rotation axis X direction.

For that reason, much of the oil OL that flows to theguide unit154 flows into the throughhole126aof thesecond box12.

Theboss part126 surrounding the throughhole126ais provided on the outer circumference of thewall part120. One end of thepipe127 is fitted into theboss part126 from the rotation axis X direction.

Thepipe127 passes through the outside of thesecond box12 and extends to thethird box13. The other end of thepipe127 communicates with theoil hole136aprovided in thecylindrical connecting wall136 of the third box13 (seeFIG.2).

For that reason, in the present embodiment, a portion of the oil OL that reaches theoil catch unit15 passes through theguide unit154 and thepipe127 and is supplied to the internal space Sc of the connectingwall136.

The oil OL discharged from theoil hole136ato the internal space Sc is retained in the internal space Sc. The oil OL lubricates the bearing B4 supported by theperipheral wall part131 of thethird box13.

A portion of the oil OL discharged to the internal space Sc passes through the gap between the outer circumference of thedrive shaft9A and the inner circumference of themotor shaft20, and moves to theother end20bside of themotor shaft20.

As shown inFIG.10, theother end20bof themotor shaft20 is inserted inside thecylinder wall part541 of theside gear54A. Aconnection path542 that communicates with the back surface of theside gear54A is provided on the inner circumference of thecylinder wall part541.

For that reason, a portion of the oil OL that moves to theother end20bside of themotor shaft20 and is discharged to inside thecylinder wall part541 passes through theconnection path542. The oil OL that passes through theconnection path542 is supplied to thewasher55 of the back surface of theside gear54A and lubricates thewasher55.

Furthermore, the oil OL that lubricates thewasher55 of the back surface of theside gear54A passes through theoil groove662 provided on thegear support part66 of thefirst case unit6 and theoil groove642 provided on thearc part641. The oil OL that passes through theoil groove642 is supplied to thespherical washer53 that supports the back surface of thepinion mate gear52 and lubricates thespherical washer53.

Also, as shown inFIG.2, the internal space Sc of thethird box13 connects with the second gear chamber Sb2 provided in thefourth box14 via theradial oil passage137, theaxial oil passage138, thecommunication hole112a, and theoil reservoir128 provided at the bottom of thesecond box12.

For that reason, the oil OL inside the internal space Sc is held at a position at the same height at which the oil OL is retained inside thefourth box14.

In this way, much of the oil OL scooped up by thedifferential case50 rotating around the rotation axis X flows into theoil catch unit15. The oil OL is supplied from theoil catch unit15 to inside thesupport unit145 of thefourth box14 and lubricates the bearing B2. The oil OL is also supplied from theoil catch unit15 to the internal space Sc inside thethird box13 and lubricates the bearing B4.

Also, the oil OL that lubricates these bearings B2, B4 is ultimately returned to inside thefourth box14, and scooped up by the rotatingdifferential case50.

Thus, in thepower transmission device1, the oil OL inside thefourth box14 is scooped up during rotation of the drive wheels W, W, and is used for lubrication of the bearings and engagement parts between gears with each other. The oil OL used for lubrication is returned to inside thefourth box14 and made to be able to be scooped up again.

As described above, thepower transmission device1 of the present embodiment has the following configuration.

(1) Thepower transmission device1 comprises thedifferential mechanism5, the differential case50 (case) that houses thedifferential mechanism5, and the stepped pinion gear43 (pinion gear) supported by thedifferential case50, inside the fourth box14 (box). Thefourth box14 has a support stand151 (shelf part) above the horizontal line HL that passes through the rotation axis X that is the revolution center of the steppedpinion gear43.

The oil OL scooped up by the rotation of the steppedpinion gear43 is caught on the upper side of thesupport stand151, in other words, the surface of thesupport stand151, or in theoil guide152 placed on thesupport stand151. As a result, it is possible for the oil OL to be sent into various locations from the upper side of thesupport stand151. Specifically, by providing thesupport stand151, it is possible to increase the degree of freedom in designing the supply of the oil OL scooped up by the rotation of the steppedpinion gear43.

(2) Thesupport stand151 has theoil hole151athat opens facing upward.

The oil OL scooped up by the rotation of the steppedpinion gear43 and has fallen onto the upper side of thesupport stand151 is introduced to theoil hole151athat is open upward. This configuration makes it possible to guide the oil OL more efficiently to theoil hole151athan in a configuration in which it is introduced from theoil hole151aopen facing sideways.

(3) Thepower transmission device1 has the oil guide152 (catch member) provided on the top part of thesupport stand151. The notch part155 (introduction port) that guides the oil OL to theoil hole151ais provided on theoil guide152.

When the oil OL is caught by theoil guide152 provided on the top part of thesupport stand151, using gravity, the oil OL is introduced from thenotch part155 to theoil hole151aprovided in thesupport stand151. With this configuration, it is possible to use the oil OL efficiently. With the embodiment, thenotch part155 is provided as an introduction port, but the form of the introduction port is not limited. For example, the introduction port can also be an oil hole provided on the bottom part or the side surface of theoil guide152.

(4) In theoil guide152, the guide unit154 (branch port) that guides the oil OL to a location other than theoil hole151ais provided.

The amount of the oil OL that can pass through theoil hole151aformed on theoil guide152 is smaller than the volume of the oil OL that can be caught by theoil guide152. For that reason, the surplus oil OL caught by theoil guide152 is branched by theguide unit154 and used for lubrication of other locations. With this configuration, it is possible to use the oil OL effectively.

(5) Theoil guide152 has the inclined part157 (first inclined surface) connected to theguide unit154, and the inclined part156 (second inclined surface) connected to thenotch part155. The inclination angle α of theinclined part156 is smaller than the inclination angle β of theinclined part157.

The oil OL flows according to gravity by the twoinclined parts156,157, so it is possible to guide the oil OL smoothly to thenotch part155 and theguide unit154 that theinclined parts156,157 are connected to. Furthermore, the inclination angle α of theinclined part156 connected to thenotch part155 is made gentler than the incline angle β of theinclined part157. As a result, in theinclined part156, the oil OL does not immediately flow to thenotch part155, and is temporarily held on theinclined part156. By using this configuration, it is possible to increase the oil OL holding function in thecatch unit153 of theoil guide152.

(6) Thepower transmission device1 has thering gear42 that engages with the steppedpinion gear43. Thefourth box14 has the support wall part146 (ring gear support part) that engages with thering gear42. Thesupport wall part146 has the communication port147 (notch) at a position adjacent to thesupport stand151 in the circumferential direction.

By providing thecommunication port147 on thesupport wall part146 that engages with thering gear42, it is possible to supply the oil OL to the support stand151 more smoothly. In specific terms, a portion of the oil OL that scatters by the rotation of the steppedpinion gear43 jumps over the outer circumference side of thering gear42 and scatters in the direction facing thesupport stand151. Thesupport wall part146 that engages with thering gear42 can obstruct the oil OL facing thesupport stand151. In light of that, thecommunication port147 is provided in thesupport wall part146, and guides the oil OL to thesupport stand151. Forming a notch as thecommunication port147, said another way, means that thesupport wall part146 that engages with thering gear42 is arranged at both sides sandwiching the notch. Specifically, the configuration of the embodiment means a configuration that increases the stability of the support of thering gear42.

(7) Thesupport wall part146 has a shape of the letter C.

Thesupport wall part146 may also be configured from a plurality of individual support parts arranged on the outer circumference of thering gear42, for example. However, by forming thesupport wall part146 in a C shape seen from the rotation axis X direction, making a shape that surrounds the outer circumference of thering gear42 as shown in the embodiment, it is possible to increase the surface of the portion that supports thering gear42. By using this configuration, it is possible to increase the support stability of thering gear42.

Thepower transmission device1 of the present embodiment has the following configuration.

(8) The power transmission device (1) has themotor2 arranged upstream of the transmission route of the rotation drive force of thesun gear41 that engages with the steppedpinion gear43, and thedrive shaft9A (drive shaft) connected to thedifferential mechanism5. Thedrive shaft9A penetrates the inner circumference of thesun gear41 and themotor2.

Thepower transmission device1 is the power transmission device for a single axle electric vehicle, and can provide a compact power transmission device.

Above, embodiments of the invention of the present application were explained, but the invention of the present application is not limited only to the modes shown in the embodiments. It can be modified as appropriate within the scope of the technical concepts of the invention.

EXPLANATION OF CODES

1: Power transmission device;2: Motor;3: Park lock mechanism;4: Planetary reduction gear;5: Differential mechanism;6: First case unit;7: Second case unit;8: Plate member;9: Drive shaft;9A: Drive shaft (drive shaft);9B: Drive shaft;10: Body box;11: First box;12: Second box;13: Third box;14: Fourth box (box);15: Oil catch unit;16: Breather chamber;20: Motor shaft;41: Sun gear;42: Ring gear;43: Stepped pinion gear (pinion gear);44: Pinion shaft;50: Differential case (case);146: Support wall part (ring gear support part);147: Communication port (notch);151: Support stand (shelf part);151a: Oil hole;152: Oil guide (catch member);154: Guide unit (branch port);155: Notch part (introduction port);156: Inclined part (second inclined surface);157: Inclined part (first inclined surface); X: Rotation axis (revolution center of the pinion gear); HL: Horizontal line; and α, β: Inclination angles.

Claims (15)

The invention claimed is:

1. A power transmission device comprising:

a box;

a case disposed in the box;

a differential mechanism housed in the case; and

a planetary gear mechanism disposed in the box and supported by the case, the planetary gear mechanism including a sun gear and a pinion gear that engages with the sun gear, wherein

the box has a shelf part above a horizontal line that passes through a revolution center of the pinion gear, and

the shelf part is arranged at a position that does not overlap the sun gear when viewed from radially above.

2. The power transmission device according toclaim 1, wherein

the shelf part has an oil hole that is open facing upward.

3. The power transmission device according toclaim 2, further comprising

a catch member provided on a top part of the shelf part, wherein

an introduction port that guides lubrication oil to the oil hole is provided on the catch member.

4. The power transmission device according toclaim 3, wherein

the catch member has a branch port that guides the lubrication oil to a location other than the oil hole.

5. The power transmission device according toclaim 4, wherein

the catch member has a first inclined surface connected to the branch port, and a second inclined surface connected to the introduction port, and

an inclination angle of the second inclined surface is smaller than an inclination angle of the first inclined surface.

6. The power transmission device according toclaim 5, further comprising

a ring gear that engages with the pinion gear, wherein

the box has a ring gear support part that engages with the ring gear, and

the ring gear support part has a notch at a position adjacent to the shelf part in a circumferential direction.

7. The power transmission device according toclaim 6, wherein

the ring gear support part has a letter C shape.

8. The power transmission device according toclaim 7, further comprising

a motor arranged upstream of a sun gear that engages with the pinion gear, and

a drive shaft connected with the differential mechanism, wherein

the drive shaft penetrates inner circumferences of the sun gear and the motor.

9. A power transmission device according toclaim 8, wherein

when seen from an axis direction, the shelf part is arranged so that a top surface of the shelf part is lower than a highest position of an outer circumference position of a rotation orbit of the pinion gear.

10. A power transmission device according toclaim 9, wherein

the pinion gear is a stepped pinion gear, and

the rotation orbit of the pinion gear is a rotation orbit of a large diameter gear part of the stepped pinion gear.

11. The power transmission device according toclaim 1, further comprising

a ring gear that engages with the pinion gear, wherein

the box has a ring gear support part that engages with the ring gear, and

the ring gear support part has a notch at a position adjacent to the shelf part in a circumferential direction.

12. The power transmission device according toclaim 11, wherein

the ring gear support part has a letter C shape.

13. The power transmission device according toclaim 1, further comprising

a motor arranged upstream of a sun gear that engages with the pinion gear, and

a drive shaft connected with the differential mechanism, wherein

the drive shaft penetrates inner circumferences of the sun gear and the motor.

14. A power transmission device according toclaim 1, wherein

when seen from an axis direction, the shelf part is arranged so that a top surface of the shelf part is lower than a highest position of an outer circumference position of a rotation orbit of the pinion gear.

15. A power transmission device according toclaim 14, wherein

the pinion gear is a stepped pinion gear, and

the rotation orbit of the pinion gear is a rotation orbit of a large diameter gear part of the stepped pinion gear.

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